1. Field of the Invention
This invention relates to swivel joints, and more particularly relates to torsionally controlled swivel joints having a readily adjustable torque element within the flow passages and between the sections of the joint for counteracting rotative forces acting on one section relative to the other.
2. Description of the Prior Art
In flexible conduit systems such as loading arms for transferring liquids between storage areas and tank trucks, railroad cars, or ships; swivel joints are used to interconnect the inboard loading arm in flow communication with a riser pipe or the like. It is quite common in such conduit systems to balance the rotational forces acting on the two sections of the swivel joint by external counterbalancing weights, hydraulic cylinders, spring and lever arm assemblies, and pulley and cable systems or the like. Such prior art systems include many external parts which are not only expensive but get in the operator's way and sometimes cause physical injury to the operators as well as damage to the equipment itself.
One such prior art device is illustrated in assignee's U.S. Pat. No. 3,378,033 which issued to Cooley, Jr. on Apr. 16, 1968. This patent illustrates a balancing mechanism for a loading arm which uses a torsion spring and lever arm with a ratchet type adjustment device for varying the spring tension as desired. All of the components of the balancing mechanism are external of the flow passages of the loading arm.
A similar external counter balancing mechanism which utilizes a torsion spring is illustrated in U.S. Pat. No. 2,739,779 which issued to Krone et al. on Mar. 27, 1956.
U.S. Pat. No. 2,792,158 which issued to Veitch Sr. et al. on May 14, 1967 discloses a conduit system for draining tanks or the like which includes a two-piece flexible joint. The two pieces of the joint are held together by a tension spring, not a torsion spring, which spring lies within the flow passages of the pumping system.
Torsion springs are also used within the housings of flexible joints of adjustable lamp assemblies or the like for counterbalancing and supporting the weight of the lamp housing. One such device is disclosed in U.S. Pat. No. 2,694,585 which issued to Fiori on Nov. 16, 1954. However, the joint is clearly not a part of a conduit system for flowing fluids.